Embodiments relate semiconductor technology. Some embodiments relate to an image sensor and a method of fabricating an image sensor.
An image sensor may include a semiconductor device which may convert an optical image into an electrical signal. An image sensor may include charge coupled devices (CCDs) and/or complementary metal oxide silicon (CMOS) devices. An image sensor may include a light receiving region having a photodiode which may sense light, and/or a logic region which may process sensed light into an electrical signal data. Efforts may have been made to maximize optical sensitivity. Example FIG. 1A is a plan view illustrating a microlens of a CMOS image sensor. Example FIG. 1B is a sectional view of FIG. 1A cut along a line I-I′.
Referring to FIG. 1A and FIG. 1B, a light receiving region including a photodiode is schematically shown, excluding a logic region. An image sensor may include semiconductor substrate 10. An image sensor may include a plurality of microlenses 70 arranged corresponding to red (R), blue (B) and/or green (G) color filters formed on and/or over semiconductor substrate 10. An image sensor may include a plurality of photodiodes disposed on and/or over an active region of semiconductor substrate 10, an interlayer dielectric formed on and/or over an entire surface of the semiconductor substrate 10 which may include metal lines, a dielectric film formed on and/or over an interlayer dielectric, a filter array including R, B and/or G color filters arranged corresponding to photodiodes on and/or over a dielectric film, and/or a planarization layer formed on and/or over a filter array.
A 0.18 μm image sensor may employ single microlenses. However, as an image sensor may be developed to be smaller than 0.13 μm, sensitivity may be minimized owing to gaps generated among single microlenses. Dual microlense technology may be introduced. Dual microlenses generate substantially no gaps and/or may be capable of compensating for minimized sensitivity by between approximately 10% and 20% relative to single microlens. Dual microlenses may be capable of transmitting data of relatively more light to photodiodes relative to single microlens, thereby maximizing sensitivity.
Dual microlenses may exhibit problems, for example of a corner gap and/or a lens curvature. Since dual microlenses may be a type of planner-type microlens, curvatures may be substantially same in a vertical direction and in a horizontal direction of dual microlenses, but a curvature in a diagonal direction may be different. A single microlens may also include such a difference in curvature. A curvature difference may affect light condensing efficiency. Also, light may interfere with a corresponding photodiode and/or neighboring photodiodes. Noise and/or distortion may be maximized.
Accordingly, there is a need of an image sensor and a method of fabricating an image sensor which may include a microlens in which curvatures are substantially equal in a horizontal, vertical and/or diagonal directions.